The closure of Harbour Pinnacle on Minden Avenue started at 7pm and is expected to last until 7am on Wednesday.
People who live there are required to get a swab test done before midnight.
Anyone who has been present at the building for more than two hours from October 18 is also required to be tested before November 11.
The government said in a statement the person who lives at Harbour Pinnacle arrived from overseas and tested preliminary positive on Tuesday.
“[T]he risk of infection in the relevant area is assessed to be likely higher, so the government decided to make a ‘restriction-testing declaration’ for the relevant area after the test result was found to be positive,” it said.
The Department of Health later said the patient is a 29-year-old man who serves as cargo flight crew member. He had been fully vaccinated with the BioNTech jab
He flew to Germany on October 30, and returned to Hong Kong on November 6 aboard CX2066.
Tests prior to departure and on return to Hong Kong came back negative, but a sample collected at a community testing centre on Monday – as part of compulsory testing requirements for exempted persons – came back preliminary positive.
The department said another crew member on the same flight, a 57-year-old man who lives in a house in Headland Village in Discovery Bay, had also tested preliminary positive with the same mutant strain of the coronavirus.
Like the 29-year-old man, he had tested negative prior to departure and upon arrival, and the preliminary positive test was recorded at a community testing centre on Monday.
He had been also fully vaccinated with the BioNTech jab. Residents at his home will undergo quarantine.
The places where the two men visited during the incubation period will be included in a compulsory testing notice.
The department said it was also investigating two more preliminary positive cases, involving a 30-year-old female who arrived from the Philippines on October 17 and a 15-year-old who arrived from Italy, via Qatar, on October 14.
The 30-year-old woman tested negative six times during compulsory quarantine at the Silka Tsuen Wan Hotel. Upon completion of her quarantine there, she stayed at the Rosedale Hotel in Causeway Bay, and underwent another test on November 8, which came back positive but with a low viral load.
The 15-year-old also tested negative six times in quarantine, before moving into the Gateway Hotel, Hong Kong in Tsim Sha Tsui. She tested positive after a test in a community testing centre on November 8.
The department said these two cases could be re-positive cases, and they will be monitored. The places where these two patients resided and visited in Hong Kong during the incubation period will be included in a compulsory testing notice, it said.
Last updated: 2021-11-09 HKT 21:05